Expansion-bit



No. 624,439. Patented May 9, I899.

A. L. ADAMS.

EXPANSION BIT.

(Application filed July 22, 1898.)

(No Model.)

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UNITED STATES PATENT OFFICE.

ABRAHAM L. ADAMS, OF BRIDGEPORT, CONNECTICUT.

EXPANSION-BIT.

SPECIFICATION forming part of Letters Patent No. 624,439, dated May 9, 1899.

Application filed July 22, 1898. Serial No. 686,639. (No model.)

To (l/ZZ whom, it may concern:

Be it known that I, ABRAHAM L. ADAMS, a citizen of the United States, and a resident of Bridgeport, in the county of Fairfield and State of Connecticut, have invented certain new and useful Improvements in Expansion- Bits, of which the following is a specification.

My invention relates to an improvement in expansion-bits; and it relates to the class of rotaryboring-bits known as center bits, and particularly to center bits which are provided with adjustable cutters, wherein the tendency of the cutter unless prevented by positive means is to be forced forward under the cutting strain, and thus enlarge the hole beyond the size for which the cutter was originally set. To counteract this tendency of the cutter to crawl, many expensive devices have heretofore been employed, which adds greatly to the cost of. manufacture, and thereby detracts very materially from the commercial value of the bit. v

My improvement consists in tapering the base of the cutter in a gradually-diminishing angle toward its cutting-point or nicker, so that when secured by its clamping-plate such angular formation will effectually prevent accidental movement under the cutting strain.

To enable others to fully understand myin vention, reference is had to the accompanying drawings, in which-- Figure 1 represents a front elevation of my improved bit, showing a broken view of the shank. Fig. 2 is a view similar to Fig. 1 with the adjustable cutter and its clamping-plate removed. Fig. 3 is a similar View showing the adjustable cutter removed. Fig. 4 is a side elevation of the bit as shown at Fig. 1 looking in the direction of arrow 0;. Fig. 5 is a side elevation of the bit-as shown at Fig. 1 looking in the direction of arrow 19. Fig. 6 is a detail bottom plan view of the adjustablecutter. Fig. 7 is a side elevation of the bit with the cutter removed, showing the cutter-seat formed at right angles to the bit-head. Fig. 8 is a modified construction of the cutter, adapted to operate in the head shown at Fig. 7.

The construction and operation are as follows:

1 represents the shank of the bit, and 2 its head, which head is provided with the slot or as shown at Fig. 2, and at the same time be parallel with each-other.

The beveled edge 5 of the bit rests against the edge 9 of the seat 3, while the angle of the opposite beveled edge 5" is more acute, making the rear end 5 of the adjustable cutter wider than the forward end 5 thereby for1ning the base of the cutter tapering or wedgeshaped.

The beveled edge 4 of the clamping-plate 4, Fig. 3, is of course the same taper or angle as the edge 5 of the cutter, so that in shifting the cutter all that is necessary is simply to loosen the screw 6 and move the said cutter in either direction required. In this case, where the cutter is provided with the wedgeshaped base, the screw will have to be turned back a trifle more than ordinaryin order that the clamping-plate may have a greater vertical movement to compensate for the wedgeshaped formation of the cutter. The clamp-v ing screw and plate will easily hold the cut ter down, while its wedge-shaped formation will efiectually prevent its being drawn forward in the only direction it is liable to be accidentally moved under the cutting opera= tion.

In the modification shown at Fig. 7 the side Walls 8 and 9 of the seat 3 are formed at a right angle to the axis of the bit instead of being angularly disposed thereto, as in the other views. The forward or binding lip 4- of the clampi ng-plate would have the same angular formation as shown inthe other views, and the bit, Fig. 8, would have the same angular formation 5 to engage therewith, while the opposite edge 5 will be straight to engage the straight edge 9, Fig. 7, of the seat of the bit.

From the foregoing description it will readily be seen that my improvement has a decided advantage over cutters that are provided with teeth and pinions to prevent lon- 7 I claim as new, and desire to secure by Letters 4 Patent, is

1. The herein-described improvement in expansive bits consisting of a cutter provided 1 with a wedge-shaped base whereby the forward end of said base is made narrower than its rear endto prevent accidental displacement of said cutter under the cutting strain said cutter having a beveled edge combined with a clamping-plate having abeveled edge adapted to engage with the beveled edge of said cutter substantially as described and for the purpose set forth.

2. The combination, in an expansive bit of the character described, of the head 2 provided with a cutter-seat Whose side walls are formed parallel to each other, the cutter 5 having the singularly-formed beveled edge 5 so as to leave the front end 5 of said cutter narrower than its rear end 5, the clampingplate 4 whose cutter-engaging lip i is also beveled to correspond to the'beveled edge of said cutter and tapered to the same pitch or angle as the angularly-disposed edge 5 of the cutter, substantially as set forth.

3. The herein-described improvement in expansion-bits consisting of a cutter whose base is made narrower at the forward or cutting end than at its rear end, combined with a head portion whose forward end wall is angularly disposed, a clamping-plate whose forward end is of an opposite taper to the said end wall of the head, thus making the side supports for the said cutter to correspond to its angularly-disposed edges said cutter and clamping-plate having correspondingly-beveled engaging edges, substantially as described and for the purpose set forth.

Signed at Bridgeport, in thecounty of Fairfield and Stateof Connecticut, this 30th day of June, A. D. 1898.

, ABRAHAM L. ADAMS.

Witnesses:

DAVID M. LAOKIE, J. W. RANGE. 

